UniMoG Tech Tips
delivery of our 1963 Swiss 404 in December of 2000, we have learned
much. Mainly that they are much like Volkswagens except that the
required tools are MUCH larger and take MUCH effort just to lug them
around. We were disappointed in the quality of the Mercedes
UNIMOG workshop manual. It's not as complete as the Robert
Bentley manuals. Therefore, we have decided that as we perform
component and system level overhauls, we will share what we learn with
others. With the exception of Tip #1, the material here will be
applicable to the 404.114 model and other similar variants.
Tip #1 - Manuals
Buy the Mercedes UNIMOG Instruction manual. This small book is
invaluable for simple things like 'what does that lever do?', 'where
are all the lubrication points?', and the ever famous 'what torque do
I tighten the wheel nuts too?'. It's also a good example of a fine
manual. It doesn't cover any of the overhaul procedures but
everything you need to keep it in great shape. My favorite
section of the 404 Instruction manual are 2.3.6 and 3.3.4.
Tip #2 - Fuel Pumps
We have replaced the stock mechanical fuel pump with two 24V electric
fuel pumps. For details of our setup and how we diagnosed the
problem, click here
Tip #3 - Rant on Oil
Click here to read our in-depth rant on our
findings and what oils we're using in our engine & transmission.
Tip #4 - Transmission Temperature
Since we put over 30,000km on our truck in less than the first 3 years
of ownership, 12,000 or so of those on our new transmission, we have
made a lot of careful observations about
Tip #5 - Hazard Lights
The Swiss 404 did not come equipped with a 4-way flasher, this is one
solution to that problem.
Tip #6 - 404 Oil filter leaking? Is your 404 engine oil filter
leaking? Check carefully to see if yours has the same problem
that ours had when we got it. At some point while changing the
oil filter, someone hadn't removed the old O-ring from the filter
housing before installing the new one. Having two O-rings in
there does not help it seal or seat! Once we peeled two O-rings
out and replaced them with ONE new one, we have had no engine oil
leaks. (Hardly a German truck any more since it doesn't mark
Tip #7 - Gearshift rattling?
One of the benefits of replacing our transmission was getting a new
gearshift that didn't rattle like the old one. You might be able
to use our idea for solving your rattly
gearshift without spending quite so much time and money.
Tip #8 - Reverse Light Switch.
There are times when it is convenient to have automatic back-up
lights. Click here to see how we
made ours work.
Tip #9 - Part Numbers.
We have successfully ordered some parts from our local Mercedes Benz
car dealer. A number of tune up parts are also available from
your local auto parts store, once you convince them to look up the
part numbers correctly. Click here
for a list of current part numbers.
Tip #10 - Tires.
With over three seasons, 38,000+ km, and one flat on our first set of
Continental MPT 81's, we have some observations
Tip #11 - 12 Volt tach. installation.
In the standard 24V 404, it is rather easy to install a 12 V
tach. The negative side of the ballast resistor is the positive
side of the coil, which sees about the same voltage as the positive
side of the coil on a 12 V vehicle which uses a coil with internal
resistance (like a VW). Don't forget to give your instrument
light in the tach 12 V instead of 24!!!
Tip #12 - Tools.
It is easy to carry all the necessary tools in the stock 404 tool box
if you make tool rolls out of old jeans
to wrap them in.
Tip #13 – Engine Replacement Checklists.
Since we had our cab off twice in less than six months, to make the
second time (when we had to replace the engine) go more quickly, we
made very detailed lists of what we needed on hand & what we
needed to do. Recognizing that some items will differ from one
404 to the next, feel free to make use of our checklists
they may make the job go a little more smoothly for you!